Sigma, sigma-bis (2, 2-dialkyl-4, 5-dihydro-1, 3, 2-dithiarsenolyl) 1, 2-ethanethiols



United States Patent 3,152,159 S,S-BIS(2,2-DIALKYL-4,5-DlHYDRO-1,3,2-DI- THIARSENOLYL) 1,2-ETHANE'I'HIOLS Peter F. Epstein, Yonkers, N.Y., and George P.

Willsey, Jr., Houston, Tex., assignors to Stanfiel- Chemical Company, New York, N.Y., a corporafion of Delaware No Drawing. Filed Oct. 3, 1961, Ser. No. 142,533 3 Claims. (Cl. 260-440) This invention relates to organoarsenic compounds and, in particular, to S,S-bis(2,2-dialkyl-4,5-dihydro-l,3,2-dithiarsenolyl) l,2-ethanetl1iols and to a method of preparing them. The invention also pertains to biocidal compositions containing as the active component thereof, at least one of the aforesaid organoarsenic compounds and to methods of formulating, using and applying such compositions.

The use of arsenic and its compounds as a pesticide has long been known to the art and many commercial biocides utilize arsenicals as their toxicant component. However, it is worth while to note that inorganic compounds of arsenic, particularly the heavy metal salts, are the predominant derivatives which are employed in such commercial applications. Although in recent years, organic arsenic compounds have been prepared and tested for pesticidal use, these investigations represent a relatively small area being confined largely to the medical field. The investigations of Ehrlich in connection with the trypanosomidal activity of organic arsenicals is particularly noteworthy in this connection. An interesting finding of Ehrlichs researches revealed that pentavalent arsenic compounds were inactive in vitro whereas the trivalent derivatives possess high activity and a theory was put forth at that time attributing the in vivo activity of arsenic compounds as a consequence of its reduction to the trivalent form in the animal organism. Later works,

3,152,159 Patented Oct. 6, 1964 methyl, ethyl, n-propyl, isopropyl and the like. Specific structures which are illustrative of the foregoing formula include the following configurations:

(Compound 1) In preparing the herein contemplated organoarsenic derivatives, about 3 moles of 1,2-ethanedithiol are condensed with about 2 moles of a dialkylarsinic acid. The reaction, which proceeds smoothly and in good yields, is considered to take place in accordance with the equation as schematically outlined below wherein the lower dialkylarsinic acid is dimethylarsinic or cacodylic acid:

CH s H (3H3 ([3153 H S OH CH2-S CH3 CH2 S-CH:

2 1 0 =As-@sornomsm-As= 0 As-somornss 4Hz0 orrrs n I H SCH2 on om oars CH3 on, s-on,

for example King and his collaborators, showed that certain trivalent arsenic compounds possess little or no activity in vivo, and it was suggested that such arsenic derivatives are resistant to reduction in vivo or perhaps were excreted too rapidly before they could be reduced by the organism.

During the course of our investigations into organic arsenic derivatives, we discovered a class of organoarsenic compounds not previously contemplated by the prior art and the provision of such arsenic compounds and the method of making them constitute a primary object and purpose of this invention. It is also an important object and aim of this invention to provide pesticidal compositions which embody or incorporate the herein described organic arsenicals as the active component. Another important object of the invention is to provide means of using and applying the aforesaid compositions. Other objects and purposes will become apparent as the description proceeds.

The organoarsenic compounds which constitute the subject matter of this invention can be generally represented by the formula:

wherein R and R designate lower alkyl groups, e.g.,

27.6 g., 0.2 mole of cacodylic acid, 29.2 g., 0.3 mole of 1,2-ethanedithiol and 200 ml. of benzene were placed in a flask equipped With a Dean and Stark trap and the mixture refluxed for 6 hours. During this period, the cacodylic acid dissolved with production of a homogeneous colorless solution. 7.2 mls. of water, corresponding to the theoretical amount of 0.4 M was collected in the Dean and Stark receiver. After distilling oif the solvent, the residue of colorless oil amounted to 40.2 g., representing a yield of 86%.

In this instance, the procedure of Example 1 was followed excepting the cacodylic acid of the previous example was replaced by diethylarsinic acid. In general, the results and yields paralleled those of Example 1.

As previously pointed out, the organoarsenic compounds of this invention are useful as toxicants in compounding various biocidal compositions which have been found useful for combating both plant and animal activity. For instance, Compound 2 was found to be an effective herbicide when applied in the form of a post-emergent treatment to many different types of weeds, and similar noxious growths. When applied at the rate of 2-5 lbs.

per acre, the toxicant of Compound 2 was capable of controlling various broad leaf plants as well as crab grass. The organoarsenicals of the invention were also found to exhibit microbiocidal properties, and in this connection, it is to be noted that 5 p.p.m. of Compond 2 gave complete control of Escherichia coli whereas 3 ppm. inhibited the microorganism.

In ascertaining the microbiocidal characteristics of the herein contemplated compounds, 1 oz. bottles are partially filled with ml. of malt or other suitable nutrient broth. These are capped with aluminum foil, sterilized and so maintained for tests. The toxicant to be tested is injected with a syringe through the foil into the broth, which is then inoculated with Water suspension of spores of the microorganism. The bottles are sealed and held for one Week and the results noted.

In preparing herbicidal compositions, containing as the toxicant thereof, the arsenicals of this invention, it is a common practice to use various diluents, carriers and other adjuncts which are common to the art. For instance, liquid dispersions may consist of a water base or oil base or may be mixtures of oil and water, suitably homogenized to suspend the active component. Aqueous colloidal dispersions can be formulated by dissolving the active component in a water immiscible organic solvent followed by homogenization by mechanical means such as a homogenizer with or without an emulsifying agent. Alternately, the active component can be dissolved in a small amount of Water miscible solvent and the resultant solution diluted with water to form a suspension of solid particles in the aqueous media. This particular type of formulation is preferably compounded using a surface active agent to facilitate formation of the dispersion. Typically 0.75 g. of the compound to be tested as a herbicide is dissolved in 1015 ml. of acetone and the resultant solution diluted with 150 ml. of water using Methocel (methylated cellulose) and Vatsol (sodium salt of isopropylnaphthalene sulfonate) as surface active agents.

In the event that it is desired to apply the toxicant as a solid or as a dust, then it is preferable to admix it with a finely divided pulverulent solid as exemplified by clay, talc, diatomaceous earth and precipitated chalk. By incorporating Wetting agents to the aforesaid compositions, the dispersibility in water is thereby increased.

Treatment of the weeds or plants comprised spraying the foliage after it had reached a height of 3 to *6 inches; the results were noted 2 weeks following the spray treatment.

The results obtained in testing the organorsenic compounds of the invention showed them to be effective against a wide variety of noxious plant growths, for instance Compound 2 when applied at a concentration of 2 lbs. per acre was effective in controlling or eradicating crab grass, alfalfa, dodder, Jimson weed, bind weed, mustard and pig weed.

We claim:

1. An organoarsenic compound having the following formula:

wherein R and R designate lower alkyl groups.

2. An organoarsenic compound, having the following formula:

3. A method for preparing an organoarsenic compound having the following formula:

which comprises reacting about 3 moles of 1,2-ethanedithiol with about 2 moles of a lower dialkyl arsinic acid under conditions which provided for azeotropically removing the water from the reaction and isolating the so formed organoarsenic compound.

References Cited in the file of this patent UNITED STATES PATENTS 2,644,005 Urbschat June 30, 1953 2,769,702 Sowa Nov. 6, 1956 2,937,081 Nolan May 17, 1960 3,013,041 Aftandilian Dec. 12, 1961 OTHER REFERENCES Rueggeberg et al.: J.A.C.S., vol. 68, pages 1860-1862 (1946).

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,l52 159 October 6, 1964 Peter F Epstein et a1 It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Columns 1 and 2, the right-hand portion of the formula should appear as shown below instead of as in the patent:

CH --S\ 3 GH3 S CH As-SCH CH S-As +4H O CH S S CH column 4, line 43 for "provided" read provide Signed and sealed this 19th day of January 1965.

(SEAL) Attest:

EDWARD J, BRENNER ERNEST W. SWIDER Attesting Officer Commissioner of Patents 

1. AN ORGANOARSENIC COMPOUND HAVING THE FOLLOWING FORMULA: 